FUNCTIONAL-CHANGES APPROPRIATE FOR DETERMINING MINERAL ELEMENT REQUIREMENTS

One factor limiting efforts to determine human requirements for dietar y intakes of mineral elements has been the unavailability of acceptabl e standards for evaluating the effects of marginal and mild deficienci es. Traditional approaches, such as growth, longevity, chemical balanc e and measurement of concentrations of minerals in plasma or serum and cellular components of the blood, have not been sensitive indicators of mineral nutriture. One alternative that has been shown to be respon sive to graded dietary mineral intake is the evaluation of functional responses to specific challenges or stressors. Aberrant responses, eit her exaggerated or attenuated, to controlled stressors have been obser ved in a variety of physiological, psychological and immunological par ameters when mineral intakes have been suboptimal by conventional stan dards, compared with adequate responses. In comparison to static bioch emical approaches for assessment of mineral nutritional status, functi onal tests may be sensitive and responsive to alterations in mineral i ntake in adult humans. Dynamic functional measures complement static b iochemical measures and reflect the net effect of deficiencies on inte grated biological systems. The application of some of these types of d ynamic evaluations of function may be a useful and productive approach for proposing mineral element intakes to optimize human health and bi ological function and performance.